The invention relates generally to engines, and more particularly, to an engine diagnostic system and method for detecting a hardware anomaly.
Typically, in internal combustion engines, air enters through an intake manifold and mixes with a fuel to form an air-and-fuel mixture. The air-and-fuel mixture is combusted within a plurality of cylinders to drive pistons which rotatably turn a crankshaft to produce drive torque. In certain instances, the air-and-fuel mixture in a particular cylinder may combust at an undesired time. More specifically, temperature and/or pressure of the air-and-fuel mixture may exceed a critical level, causing the air-and-fuel mixture to ignite automatically prior to a normal ignition. The automatic ignition of the air-and-fuel mixture at an undesired time may be termed as “pre-ignition.” Such a pre-ignition may result in engine knock. For example, engine knock may be a noise/vibration resulting from a rapid increase in cylinder pressure. Engine knock over a sustained period of time may affect other components of the engine.
Engines may use control systems including misfire detection systems and/or knock detection systems that determine if and when an engine knock occurs. Such engine control systems regulate engine operation to reduce or prevent engine knock. Preventing engine knock may enhance engine performance and/or vehicle drivability. However, the use of such conventional control systems has drawbacks associated with false outputs flagged by the knock sensor. Moreover, there are uncertainties in determining as to what component has failed when knock or misfire is detected.
There is a need for an enhanced engine diagnostic system and method.